Flow measurement plays an important role in industrial production, process control and energy utilization. The steam flow is affected by the state of steam properties and the design of the steam flowmeter during the measurement process, resulting in low measurement accuracy. Based on the combined measurement method of differential pressure flowmeter and vortex flowmeter, an integrated flow measurement device that integrates averaging-velocity tube and piezoelectric vortex flowmeter is proposed in this paper. It combines the structural features and advantages of the two flowmeters scientifically. In this paper, the differential pressure transmitter is used to detect the pressure difference on both sides of the cylinder. Due to fluid vibration and piezoelectric effect, the probe in the device generates regular vibration. And combined with Digital Signal Processing (DSP) technology and automatic frequency band adjustment method, the flexibility and stability of frequency signal processing are improved. The measurement performance of the device was evaluated in this paper. The experimental results show that the absolute value of the relative error of the device is within 1.00% and 1.50% under the conditions of single-phase water and single-phase gas, respectively. The device can achieve dualsignal measurement, and it has the advantages of wide applicability, good stability and strong anti-interference, which will provide a new design idea for the measurement of saturated wet steam.